Casing centralizer



June 5, 1951 R c. BAKER 2,555,628

CASING CENTRALIZER Filed March 8, 1948 B 13 J 1, I 17 22 2g 11 18 a l 18 J6 20 f5 1 18 a? 5 22 10 r "w 22 J6 22 if I ..1 1g 10a, 19 19 l I? 14 I H.

, INVENTOR. Reuse/v CT fiAKEQ, B BY Patented June 5, 1951 CASING ,CENTRALIZER Reuben C. Baker, 'Coalinga, Galif., assignor to Baker- Oil Tools, -Inc., Vernon, Califl, a..co1:po-

ration of California ApplicationMarch 8, 1948, Serial No. 13,723

8 Claims.

The present invention relates to devices for centering well casin liners, and similar conduits in well bores.

Centralizing devices employing outwardly bowed springsare used for centerin well casing and the like in well bores. A preferred arrangement insures the pulling, as distinguished from pushing, of the centralizer through restrictions in the well bore, regardless of the longitudinal directionpf mOvement of the Well casing, to avoid bucklin of the outwardly bowed springs and their possible breaking. These preferred forms, as heretofore constituted, have inherent limitations on ,the size borehole in which they can be used. They have not lent themselves to use in so-called slim holes of onlyslightly greater diameter than the diameter of the casing on which they are vention to provide a casing centering device,

which can be collapsed inwardly to an effective maximum external diameterthat is only slightly greater than the external diameter of the casing I o w c he evice may b mo ted- Another obj ect of the invention is to provide. a casing centering device embodying outwardly bowed springs, which can be pulled through the Well bore, and which consists of relatively few par s h t re econom l t m nufactur an assemble.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of an embodiment of the invention. For this purpose, there is shown a form in the drawings accompanying and forming part of the present specification. This form will now be described in detail, illustrating the general principles of the invention; but itis to be understood that this detailed description is not to be taken in a limiting sense, since the scope of this invention is best defined by the appended claims.

Referring ,to the drawings:

Figure l is a side elevation of a casing centeringdevice mounted on a casing section, with its 2 V purpose of-centering-devicesis to dispose the..casing 13 centrally of the-bore hole C.

The centering deviceincludes .a plurality of circumferentially spaced, outwardly bowed .leaf springs lllwhose upper and lower ends .lql, ;,l2.ar,e attached to upper end lower collars J13, .14, re.- -spectively, that are slidable alongthe .casingsection B. Theends |l,-l2 of the L-springs l0 abut the inwardly-facing ends l5, I 6-of:the collars, to which they are butt welded. An efficienteweld can bemade through use iof an atomic hydrogen arc, a bead I! i being run along the abutting .ends of-the collar and each spring, which. projects but little, if at all, beyond thev outeradiacent. surfaces of-the collar and spring.

The leaf springs 10, as welded to the upper and lower collars I3, 14, areslidably mounted .upon a casingsection B the springs occupying theirin- -herently outwardly bowed. position, such 1 as. illustrated in FigQ-l. It is desired to pull thecentralizing device Athrough the welllbore C, asdistinguishedfrom pushing suchdevice. through. the well bore, upon movementlof the casing string through the well bore in either longitudinal direction. To achieve thispurpose, suitablestop mein- "hers, suohas lugs-18, l.9,.are.:placed atspaced intervals adjacent the inner ends 15,116 of thelup- -per and-lower collars 1| 3,. l4 between., leaf springs 10. The lugs-lfi adjacent: .the upper-collar ,,I.3..are

in transverse alignment, because of their .abutting with the latter, and this is also true .of the lower set of stop members or lugs HI -which are :transversealig-nment by virtue of their abutting with .th inner end :lE .of' the lower collar L4. When properl placed lonethe casing 13, the lugs 18, 9 iare securedr-toiit byameans .of .a plug .weld 20 disposed within .aiholetl I in, each lug. and integrated with the casing.

The provision. of tthe upper and lower sets of .stop memberscl 8, l=9:between@the upper and lower collars- 3, -14 and adjacenttheirtinnenends.1125, 1| 6 insures the pulling of the centralizing ,device through thewell bore. As. istevident from. Fig. 2, downward movement of the casing string Bin the well bore causesthe-lower stop'lugs I 9 to engage the lower collar Id and pull the springs l0 down- .in the spaces 22 between adjacent leaf springs I0, since the range of movement of the lugs H3 or l9 from the collars 13 or M is insufficient to permit relative rotation of the casing to dispose the lugs I8, l9 under any springs [0.

It is to be noted that the thickness of the leaf springs l and lugs l8, l9 are preferably no greater than the thickness of the upper and lower collars I3, M, in order that these elements will not project outwardly beyond the upper and lower collars in the event it is necessary to collapse the springs [0 completely against the casing B. That is to say, the minimum efiective outside diameter of the centering device A is the diameter of the upper and lower collars i 3, l4, which enables the casing centralizer to be run in well bores whose internal diameter need have only a slight running clearance with respect to the collars l3, Hi. When used in such extreme slim holes, the springs l0 can be collapsed substantially f-ully against the casing B, leaving no elements projecting outwardly beyond the upper and lower "collars. The placing of the stops I8, i9 between the springs permits such full collapsing to occur. Of course, the springs will expand and exert the necessary forceto maintain the casing centered in bore holes that are substantially greater in diameter than the casing string and upper and lower collars l3, [4.

It is, accordingly, apparent that a simple and inexpensive casing centralizer has been provided whose minimum effective external diameter is very little greater than the external diameter of the casing section B itself, on which the casing centralizer is slidably mounted. As a matter of fact, the outside diameter of the collars l3, l4

need be no greaterthan the external diameter of the usual couplings securing adjacent casing sections together. The centralizer, therefore, imposes no limitations on the minimum diameter bore hole in which it can be used. The side edges I 0a of the springs i0 prevent the stop members l8, l9 from inadvertently shifting under the springs H], which would prevent their full inward collapsing, while the disposition of the stop mem- 1 bers with respect to the collars themselves insures the pulling of the centralizer through the well bore upon longitudinal movement of the eastween adjacent springs; said stop means being confined from substantial angular movement by engagement with the side edges of said adjacent springs.

2. A centering device as defined in claim 1; in which said stop means and the ends of said springs do not extend laterallybeyond said member.

3. A centering device; including upper and lower spaced, generally cylindrical members; circumferentially spaced, outwardly bowed springs disposed between said members with their upper and lower ends substantially abutting and secured to the inner ends of said upper and lower members, respectively; and stop means disposed adjacent and engageable with the inner end of each of said members and, projecting laterally outward between the end portions of adjacent springs; said stop means being confined from substantial angular movement by engagement with the side edges'of said adjacent springs.

4. A centering device as defined in claim 3; in which said stop means and the ends of said springs do not extend laterally beyond said members.

5. In combination with a casing; a generally cylindrical member slidable on said casing; circumferentially spaced, outwardly bowed springs secured to an end of said member; and stop means secured to said casing and disposed adjacent and engageable with said end of said memleer and projecting laterally outward between adjacent springs; said stop means beingprevented from movement under said springs by engagement with the sides of said adjacent springs.

6. In combination with a casing; upper and lower spaced, generally cylindrical members slidable on said casing; circumferentially spaced, outwardly bowed springs disposed between said members with their upper'and lower ends substantially abutting and secured to the inner ends of said upper and lower members, respectively; and stop means secured to said casing and disposed adjacent and engageable with" the inner end of each of said members and projecting later ally outward between the end portions of adjacent springs; said stop means being prevented from movement under said springs by engagement with the sides of said adjacent springs.

' '7. A centering device; including a generally cylindrical member; circumferentially spaced, outwardly bowed springs having'ends secured to an end portion of said member; and a lug disposed adjacent and engageable with said end portion of said member and projecting laterally'out- Wardly between adjacent springs out of alignment with said springs; said lug being confined from substantial angular movement by engagement with the side edges of said adjacent springs.

8. A centering device; including upper and lower spaced, generally cylindrical members; circumferentially spaced, outwardly bowed springs disposed between said members with their upper and lower ends secured to the inner end portions of said upper and lower members, respectively; and lugs disposed adjacent and engageable with the inner ends of each of said members and projecting laterally outwardly between the end portions of adjacent springs and out of alignment with said springs; said lugs being confined from substantial angular movement .by engagement with the side edges of said adjacent springs.

REUBEN c. BAKER. REFERENCES CITED The following references are of record the file of this patent: r a r UNITED STATES PATENTS I Steps Mar. 2, 1943 

